Method for treatment of rubber and plastic wastes

ABSTRACT

A process for converting relatively ash-free solid polymeric wastes to more valuable liquid, solid, and gaseous products which comprises mixing rubber and/or plastic wastes at high temperatures in a refractory petroleum stream and catalytically cracking the mixture.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for the treatment of rubber andplastic wastes and, in particular, to a method for converting suchmaterial to liquid and gaseous fuels and chemicals by catalyticallycracking a mixture of the solid polymeric wastes and selectedpetroleum-derived streams.

2. Description of the Prior Art

Given the proliferation of used rubber tires, plastic packagingmaterials, one-way plastic containers, and by-product and substandardpolymers, improved methods of recovering the hydrocarbon valuescontained therein are needed, particularly in view of the increasingscarcity of oil and natural gas. The potentially valuable hydrocarbonsin such materials would be better utilized if an economically attractivemethod could be devised for transforming them into useful liquid, solid,and/or gaseous hydrocarbon products having utility as fuel or aspetrochemical raw materials.

Waste rubber and plastics are not conveniently burned; sulfur isreleased in the form of sulfur oxides which must be removed from thecombustion gases prior to their discharge to the atmosphere. Rubber andplastics disposed of in incinerators melt and stick to the grate of theincinerator, causing high temperatures at the grate which can damage theincinerator.

It has been proposed to pyrolytically decompose rubber and plasticwastes by feeding the wastes either directly or in the molten state to apyrolysis reaction furnace and maintaining the wastes therein for asufficient period of time to decompose the wastes. For example, U.S.Pat. No. 3,956,414 describes a method of converting solid, amorphouspolyolefin material to a liquid oil product which comprises melting thepolyolefin by heating with a petroleum hydrocarbon oil and thermallycracking the resulting melt at a temperature of about 250° to 450° C.Other variations of the pyrolytic decomposition process are described inU.S. Pat. Nos. 3,674,433; 3,823,223; 3,832,151; and 3,984,288. The chiefdisadvantage of this approach is the amount of time required for theprocess to generate useful products in that heating times in excess ofthree hours are often required to decompose the rubber and plastics.

Defensive Publication No. T940,007 describes a process for theconversion of waste rubber to produce hydrocarbon gases, low-sulfur fueloil, and a carbonaceous residue suitable for re-use as carbon blackwhich comprises heating and reacting rubber in the presence of moltenacidic halide Lewis salt catalysts.

U.S. Pat. No. 3,704,108 represents still another approach to thedisposal of rubber tires. The process of that invention catalyticallyhydrogenates scrap tires in an autoclave reactor under hydrogen pressureranging between about 500 to 2,000 psig and temperatures ranging betweenabout 660° to 850° F. The chief disadvantage of the process is the highoperating costs caused by the necessity of employing added molecularhydrogen. Additional costs are incurred by the necessity of using anautoclave reactor to withstand the high operating pressures.

SUMMARY OF THE INVENTION

Solid polymeric wastes such as rubber tires, plastic wares, plasticpackagings, scrap plastics, etc., contain high molecular weighthydrocarbon molecules. By heating these high molecular weight substancesin the presence of a petroleum oil, preferably aromatic streams such asFCC heavy cycle oil, at temperatures between 150° F and 700° F in theabsence of air and added molecular hydrogen, dispersion of the polymercan be achieved. Depending on the particular solid polymeric wasteemployed, complete dissolution may be achieved with little or no gasevolution. Furthermore, depending on the temperature used, a significantdegree of depolymerization occurs as indicated by the viscosity of thesolution or mixture. The resultant liquid resembles a crude oil and iscatalytically cracked or mixed with conventional cracking stock and thencracked to gasoline and distillates. A portion of the distillates may berecycled and used in the dispersion/dissolution step.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow diagram of a preferred embodiment of theinvention.

FIG. 2 is a graphical summary of the 800° F⁻ product distribution forthe tire component of Examples 4-14.

DETAILED DESCRIPTION OF THE INVENTION

The present invention involves the treatment of plastics which fall intovarious categories. Generally, the plastics employed are dictated bytheir commercial importance. For instance, it has been found that atypical plastics waste for disposal comprises on the averageapproximately 50 percent polyvinyl chloride, approximately 30 percentpolystyrene, and the remaining approximately 20 percent various otherplastics such as polyethylene, polypropylene, polyesters, polyacrylics,and the like. Thus, for the most part waste plastics fall into threeimportant categories: poly(halogenated hydrocarbons),poly(straight-chain olefins), and poly(vinyl aromatics). Therepresentative and most commercially important members of these threecategories are polyvinyl chloride, polyethylene, and polystyrene,respectively. Accordingly, these three particular plastics will bediscussed herein as exemplary members of the categories embraced by thisinvention and should not be considered limiting thereof.

The word rubber as used herein shall be understood to mean natural andsynthetic rubbers and includes plantation rubber, thiokols, neoprenes,nitrile rubbers, styrene rubbers, butyl rubbers, polybutadiene, siliconerubbers, acrylate rubbers polyurethanes, flurorubbers, etc.

The rubbers and plastics to be treated by this invention encompass awide variety of solid polymeric materials. The properties of thesematerials vary widely, depending on compounding, fabrication, thermalhistory, and many other variables. It is apparent that not all of thesematerials can be dissolved in the petroleum-derived streams employed inthe process of this invention. However, dissolution, while preferred isnot necessary to the operability of the process -- the dispersal of therubber and plastics in the petroleum medium and the subsequent crackingof the dispersion will normally produce highly desirable products.Nevertheless, certain polymeric materials are so resistant todecomposition by the process of this invention that it is desirable toavoid using them as feeds. Generally, such materials may be described asthermosetting resins, i.e., resins subject to crosslinking reactions attemperatures necessary to induce flow so that the ability to flow israther quickly lost in favor of form stability.

Rubbers and plastics may be treated alone or together according to theprocess of this invention. However, the solid polymeric feed should befree of inorganic material such as glass or cellulosic materials. If thematerial to be treated is soluble in the petroleum oil, the inorganic,insoluble components in the composite can be separated by filtration,sedimentation, or other known separation methods during or afterdissolution and the clarified solution can be catalytically cracked aswill be described in more detail below.

It may be desirable to subject the polymeric feed to a size reductionstep prior to the addition of the petroleum oil. If the feed isinsoluble in the petroleum oil, a size reduction step is highlypreferred. A variety of size reduction means are well known in the artand any of these means may be employed in the process of the presentinvention.

Rubber tires to be treated according to the process of this invention,are preferably pretreated for removal of metals. Pretreatment mayconsist of size reduction by conventional shredding and grindingfollowed by magnetic separation of the metals contained in the rubbertires. Although tire cord may also be removed from the rubber feed, sucha separation is not necessary according to the process of this inventionsince the fibers dispersed in the slurry feed to the catalytic crackerwill decompose at cracking temperatures.

The selected petroleum-derived streams employed in the process of thisinvention are thermally stable, highly polycyclic aromatic mixtureswhich result from one or more petroleum refining operations. Thermallystable petroleum fractions are high boiling petroleum-derived streamssuch as fluidized catalytic cracker (FCC) bottoms fractions whichcontain a substantial portion of polycyclic aromatic/naphthenichydrocarbon consituents such as derivatives of naphthalene,dimethylnaphthalene, anthracene, phenanthrene, fluorene, chrysene,pyrene, perylene, diphenyl, benzothiophene, and partially hydrogenatedforms thereof. Such refractory petroleum media are resistant toconversion to lower molecular products by conventional non-hydrogenativeprocedures. Typically, these petroleum refinery streams and recyclefractions are hydrocarbonaceous mixtures having an average carbon tohydrogen ratio in the range of 0.6 to 1.3, and a boiling point aboveabout 450° F. Representative petroleum fractions suitable for use inthis invention include FCC main column bottoms; TCC syntower bottoms;asphaltic material; alkane-deasphalted tar; coker gas oil; heavy cycleoil; light cycle oil; clarified slurry oil; anthracene oil; coal tar;mixtures thereof, and the like.

The nominal properties of suitable petroleum fractions are as follows:

    ______________________________________                                        Main Column Bottoms                                                           Sulfur                1.13%                                                   Nitrogen              450 ppm                                                 Pour Point            50° F                                            5% Boiling Point      640° F                                           95% Point             905° F                                           Conradson Carbon      9.96                                                    Clarified Slurry Oil                                                          Sulfur                1.04%                                                   Nitrogen              4400 ppm                                                Pour Point            50° F                                            5% Boiling Point      630° F                                           95% Point             924° F                                           Conradson Carbon      10.15                                                   Heavy Cycle Oil                                                               Sulfur                1.12%                                                   Nitrogen              420 ppm                                                 5% Boiling Point      450° F                                           95% Point             752° F                                           Conradson Carbon      0.15                                                    ______________________________________                                    

Catalytic cracking is the process of converting large molecules intosmaller ones by the application of heat and catalysts. Numerous methodsare known in the prior art for catalytically cracking petroleum-derivedstreams. The use of any of these methods are within the scope of thisinvention, including fluidized catalytic cracking employing afinely-divided solid catalyst which is maintained at all times as asimulated fluid by suspension in the reacting vapors or in theregenerating air, moving bed catalytic cracking, and thermofor catalyticcracking (TCC) employing a flowing bead-type catalyst.

In a "fluidized catalytic cracking" process (or FCC) catalyst particlesare used which are generally in the range of 10 to 150 microns indiameter. The commercial FCC processes include one or both of two typesof cracking zones, i.e., a dilute bed (or "riser") and a fluid (or"dense") bed. Useful reaction conditions in fluid catalytic crackinginclude temperatures above 850° F, pressures from subatmospheric to 3atmospheres, catalyst-to-oil ratios of 1 to 30, oil contact time lessthan about 12 to 15 seconds in the "riser," preferably less than about 6seconds, wherein up to 100 percent of the desired conversion may takeplace in the "riser," and a catalyst residence (or contact) time of lessthan 15 minutes, preferably less than 10 minutes, in the fluidized (ordense) bed.

The catalyst employed in the FCC reactor is characterized by a lowsodium content and is an intimate admixture of a porous matrix materialand a crystalline aluminosilicate zeolite, the cations of which consistessentially, or primarily, of metal characterized by a substantialportion of rare earth metal, and a structure of rigid three-dimensionalnetworks characterized by pores having a minimum cross-section of 4 to15 Angstroms, preferably between 6 and 15 Angstrom units extending inthree dimensions.

The crystalline aluminosilicate catalyst is intermixed with a materialwhich dilutes and tempers the activity thereof so that currentlyavailable cracking equipment and methods may be employed. In a preferredembodiment, there are utilized materials which do more than perform apassive role in serving as a diluent, surface extender or control forthe highly active zeolite catalyst component. The highly activecrystalline aluminosilicate zeolite catalyst is combined with a majorproportion of a catalytically active material which, in suchcombination, enhances the production of gasoline of higher octane valuesthan are produced by cracking with such zeolitic catalysts alone, whileconcomitantly providing a composite catalyst composition which may beused at much higher space velocities than those suitable for other typesof catalysts, and which composite catalyst composition also has greatlysuperior properties of product selectivity and steam stability.

The crystalline aluminosilicates employed in preparation of catalystsmay be either natural or synthetic zeolites. Representative ofparticularly preferred zeolites are the faujasites, including thesynthetic materials such as Zeolite X described in U.S. Pat. No.2,822,244; Zeolite Y described in U.S. Pat. No. 3,130,007; as well asother crystalline aluminosilicate zeolites having pore openings ofbetween 6 and 15 Angstroms. These materials are essentially thedehydrated forms of crystalline hydrous siliceous zeolites containingvarying quantities of alkali metal and aluminum, with or without othermetals. The alkali metal atoms, silicon, aluminum and oxygen in thesezeolites are arranged in the form of an aluminosilicate salt in adefinite and consistent crystalline pattern. The structure contains alarge number of small cavities interconnected by a number of stillsmaller holes or channels. These cavities and channels are uniform insize. The alkali metal aluminosilicate used in preparation of thepresent catalyst has a highly ordered crystalline structurecharacterized by pores having openings of uniform sizes within the rangegreater than 4 and less than 15 Angstroms, preferably between 6 and 15Angstroms, the pore openings being sufficiently large to admit themolecules of the hydrocarbon charge desired to be converted. Thepreferred crystalline aluminosilicates will have a rigidthree-dimensional network characterized by a system of cavities andinterconnecting ports or pore openings, the cavities being connectedwith each other in three dimensions by pore openings or ports which haveminimum diameters of greater than 6 Angstrom units and less than 15Angstrom units. A specific typical example of such a structure is thatof the mineral faujasite.

The effluent from the FCC reactor is subjected to a separation procedurefor removal of the suspended solid catalyst. Cyclone separators are apreferred means.

The hydrocarbon phase which is obtained from this separation procedureis passed into a product fractionator, i.e., a main column distillationunit, wherein the product stream is separated into heavy oil recyclefractions, middle gasoline fractions, and light end fractions. Theresidual fraction is a highly aromatic hydrocarbon mixture referred toas "FCC main column bottoms".

Referring to FIG. 1 of the drawings, a preferred embodiment of thisinvention is schematically portrayed wherein rubber tires are convertedin a fluidized catalytic cracking unit. Waste rubber is continuously fedthrough line 1 to shredder 5 and then passes through line 7 to grindingzone 10. The rubber is ground to a size within the range from about1/4-inch or 1/2-inch or less. The particulate rubber then passes throughline 12 to metals separation zone 15 and the metals are removed via line16. The means employed to separate metals from the particulate rubbercan be a magnetic separation device, a classification device separatingaccording to density such as shaking table, and the like. Theessentially metals-free particulate rubber leaves separation zone 15through line 18 for slurrying in zone 20 with heavy cycle oil from theproduct fractionator 70 which is introduced into zone 20 via line 19.These two feedstreams are mixed and maintained in zone 20 at atemperature within the range from about 500° to 700° F for a sufficienttime for dissolution and/or dispersion to occur. Although tire cord orother fibrous material may be left in the particulate rubber, it can beremoved either before or after tha particulate rubber is slurried withheavy cycle oil in zone 20. For example, a caustic solution can be usedto remove fibrous materials prior to slurrying in zone 20 or separationmeans such as a simple screen or filter may be used to remove fibrousmaterial from the rubber/heavy cycle oil mixture passing from zone 20.If desired, fresh feed may be added through line 22 to the modifiedrecycle feed passing through line 21 to the riser 23. The fresh feed maybe any of a wide variety of hydrocarbons ranging from naphthas to vacuumgas oils and coker distillates.

Modified recycle feed and fresh feed, if desired, are charged into a hotregenerated catalyst stream passing from the catalyst regeneration zone40 through line 42 to the riser 23 and passes through the reactor 30 vialine 33 to catalyst separation zone 50 which zone will usually be acyclone vessel. The reactor velocity is sufficient to maintain thecatalyst and any particulate rubber present in random motion with nocarryover of catalyst but complete carryover of fine, undissolved, solidcomponents of the tire-rubber compound such as carbon black and otherreinforcing or nonreinforcing rubber fillers and small amounts ofingredients such as zinc oxide and titanium oxide. This is possiblesince the catalyst employed will have a size range approaching 150microns whereas the undissolved tire-rubber components will be smallerthan 50 microns in diameter. Reaction conditions include temperaturesabove about 850° F, pressures from subatmospheric to 3 atmospheres,catalyst to feed ratios ranging from 1 to 30, feed contact times lessthan about 12 to 15 seconds in the riser 23 (preferably less than about6 seconds) wherein up to 100% of the desired conversion may take place,and a catalyst residence time of less than 15 minutes (preferably lessthan 10 minutes) in the fluidized (or dense) bed in the reactor 30.

Products disengaged from the catalyst pass from the catalyst separationzone 50 via line 55 to the secondary separation zone 60 wherein solid,undissolved tire-rubber components (e.g., carbon black) are separatedfrom the hydrocarbon product. The solids are recovered through line 62and are suitable to be reused for compounding rubber, water treatment,pigments, filler and insulation, or for combustion as a solidcarbonaceous material. The hydrocarbon product is removed from secondaryseparation zone 60 through line 66 to product fractionator 70 and isseparated into desired hydrocarbon product streams, such as gasolinewithdrawn via line 72, light cycle oil withdrawn via line 73, heavycycle oil withdrawn via line 74, a bottoms fraction withdrawn via line75, and gaseous fraction withdrawn via line 71. A portion of the heavycycle oil 74 is returned to zone 20 via line 19. The sulfur content ofthe feed rubber is converted to H₂ S and may be recovered as sulfur fromthe gaseous fraction withdrawn from the product fractionator 70 via line71 by known methods such as by processing in a Claus plant.

The spent catalyst passes from the catalyst separation zone 50 passesthrough line 52 to the catalyst regeneration zone 40 where the carbondeposited on the catalyst is burned off and the regenerated catalystagain enters the incoming charge stream via line 42 to repeat the cycle.

Although the foregoing preferred embodiment described the treatment ofrubber according to the process of this invention, plastics such aspoly(halogenated hydrocarbons), poly(straight-chain olefins), andpoly(vinyl aromatics) can be treated similarly. Of course, when plasticsare treated the secondary separation zone 60, which was described forthe treatment of rubber to remove fine, undissolved, solid tire-rubbercomponents (e.g., carbon black) is unnecessary. Similar to the treatmentof rubber, the initial plastic treatment step according to the inventioncomprises placing the plastic products in a grinding, cutting orgranulating apparatus to reduce the scrap product to particles orshreds. Any one or combination of a number of devices may be used forfragmenting or particulating the plastic including mill cutters,granulators and the like. The mill cutters may be selected from anydesired size depending on the size of the bottle, container or otherproduct which is to be ground by the cutting tool. Further, the spacingand number of teeth on the cutting head or bit may also be varieddepending on the size or size range of the particles desired to beobtained. For example, where relatively narrow plastic bottles of thetype commonly used for liquid detergents, shampoo and the like are to beground, the mill cutter surface may be between about 1 and about 2inches long and any suitable diameter. The spacing, number and depth ofthe cutting teeth may be varied as well as the speed at which the cutteris turned depending on the rate of cutting or grinding desired andparticle size.

The grinding phase may also be carried out in one or more steps asdesired. Thus, the first phase may utilize a rough grinding mill cutterwhich yields rather coarse particles, ribbons or grannules of theplastic which particles may thereafter be further directed to a finegrinding step to yield finer particles. In addition, a granulatorapparatus may be used in a single step, which apparatus is known toinclude rotor knives in combination with a sieve whereby the coarserparticles which do not pass through the sieve openings or apertures arefurther ground or cut until the desired small particle size is achieved.Again, such apparatus is well known to those skilled in the art and neednot be described in further detail. Obviously, depending on the type ofgrinding equipment used, be it rough or fine, particle sizes will vary.However, particles capable of passing through 5-25 mesh screens will besuitable for most uses.

It may be desirable to employ a second step which comprises washing ofthe ground plastic particles to remove non-plastic materials such aspaper, labels, container residue, metal particles and the like. Inaddition, if extensive non-thermoplastic materials are present such asbottle caps and the like, these may be removed prior to the initialgrinding step. For example, the bottles or containers may be passedthrough pinch rollers and over-sized grates whereby the smaller crackedbottle caps, etc. will be separated by falling through the grate.

The washing step is accomplished by any desirable means such as soakingthe plastic particles in a liquid, usually aqueous, with suitableagitation. The liquid should be of a specific gravity so that theplastic particles may be floated away from the non-plastic materials andthereafter recovered on a sieve or screen. If a further fine grindingstep is then desired, depending on the apparatus chosen, it may then becarried out on the recovered plastic particles.

During the grinding or granulating phase, it may also be desirable touse an antistatic agent -- especially where the particles are subjectedto a fine grinding operation. It has been found that where relativelysmall particles are produced, the static electrical charges may causedifficulty in handling or recovering the particles from the cutter.Accordingly, when the wash solution contains antistatic agents such ashigh molecular weight fatty alcohols or other known polymeric antistaticagents, the static electrical problems will be obviated.

In the case of rubber and plastic wastes containing high concentrationsof poly(halogenated hydrocarbons) such as polyvinyl chloride, theprocess of this invention provides a convenient way of eliminating thehalogen. For example, when polyvinyl chloride is treated, HCl may beseparately recovered from the gaseous fraction withdrawn from theproduct fractionator 70 via line 71 by known methods such as byscrubbing.

The present invention will be further described by the followingspecific examples which are given by way of illustration and not aslimitations on the scope of the invention.

EXAMPLE 1

Used whole tire was dissolved in Torrance heavy cycle oil at 650° F in 1hour. No gaseous product was produced. The tire/cycle oil solution wassuitable for use as a feed to a catalytic cracking unit.

EXAMPLE 2

Polyethylene bag was dissolved in Torrance heavy cycle oil at about 400°F in 20 minutes. No gaseous product was formed. The polyethylene/cycleoil solution was suitable for use as a feed to a catalytic crackingunit.

EXAMPLE 3

Polystyrene foam was dissolved in Torrance light cycle oil at 150° F in10 minutes. When the polystyrene concentration was increased to 40percent by weight, the resulting solution became highly viscous.

EXAMPLES 4-14

Whole tire was first dissolved in heavy cycle oil. Dunlop tire (rubberand fibre only) was shredded. Tire (75 grams) and Torrance FCC heavycycle oil (HCO) (75 grams) were then heated in a stirred autoclave for 3hours at 575° F. The tire completely dissolved to give a pasty material.A control run was also carried out using HCO in the absence of tire.

The rubber/HCO solution and HCO were then cracked. The crackingapparatus consisted essentially of a vertical downflow, annular vycorreactor charged with 5 grams 14/30 silicaalumina (46AI) followed by 10mls 14/30 vycor chips. The catalyst was pretreated at reactiontemperature (900° or 950° F) for 1 hour. The liquid/paste (0.1 gram) wasinjected every minute directly onto the catalyst from a metal syringeinternally threaded so that one complete turn of the barrel correspondedto 0.4 to 0.45 gram. Helium passed through the reactor continually. Gasand liquid fractions were collected. The liquid was analyzed by gaschromatography using a silicone gum rubber column. Coke (includingcarbon black) was estimated by weighing the reactor before and aftereach run. For thermal runs, a reactor packed completely with 14/30 vycorchips was used.

When enough sample was available (about 1 gram as in examples 1a, 1b,2a, 2b below) vacuum distillations were done to yield 800° F⁻ and 800°F⁺ fractions. In these instances the total 800° F⁺ fraction comprisedthe sum of both the 800° F⁺ residue from the distillation and the 800°F⁺ "tail" determined by gas chromatographic analysis of the 800° F⁻fraction.

Complete results are shown in Table I.

In order to determine whether synergistic effects occur when mixtures ofrubber and HCO are fed to a catalytic cracker, the results of Examples10, 11, 12 and 14 were analyzed to "back-out" values for the tire andheavy cycle oil components of the feed. A summary of yields calculatedby this analysis are shown in Tables II and III.

                                      Table I                                     __________________________________________________________________________    Pulse-Cracking of Whole Tire/Heavy Cycle Oil (1:1 Mixture)                                     F.C.C. Heavy Cycle Oil (HCO)                                                                           Tire/HCO (1:1 mixture)              Example No.      4   5   6   7   8   9    10  11  12   13  14                 __________________________________________________________________________     Pretreatment Temp. (° F)                                                                    ##STR1##                                                                                           ##STR2##                            Time (hr)                                                                                          ##STR3##                                                                                           ##STR4##                           High Temperature Treatment                                                      Reactor Packing                                                                               --  --  Vycor                                                                             ##STR5##     --  Vycor                                                                             ##STR6##                    Temperature (° F)                                                                      --  --  950 950 900 900  --  950 950  900 900                 Apparent Contact Time (sec).sup.(a)                                                           --  --  0.38                                                                              0.38                                                                              0.75                                                                              0.75 --  0.38                                                                              0.38 0.75                                                                              0.75                Weight of Feed (g)                                                                            --  --  2.32                                                                              2.58                                                                              2.15                                                                              1.91 --  1.86                                                                              1.20 2.18                                                                              1.43                Recovery (wt.%) --  --  107 85  99  105  --  112 124  104 110                Product Yield.sup.(b)                                                          Gas             0   0   0   2.74                                                                              0   0    0   0   8.04.sup.(c)                                                                       0   6.96                Liquid 420F.sup.-                                                                             .15 .13 .13 3.00                                                                              3.44                                                                              3.50 0   0.54                                                                              4.02 2.07                                                                              7.89                420F to 650F    31.69                                                                             32.31                                                                             25.72                                                                             34.53                                                                             40.57                                                                             38.27                                                                              14.91                                                                             23.78                                                                             29.99                                                                              26.35                                                                             35.28               650F to 800F    62.26                                                                             61.38                                                                             65.78                                                                             47.54                                                                             45.34                                                                             51.29                                                                              37.26                                                                             35.37                                                                             29.46                                                                              38.64                                                                             25.46               800+            2.10                                                                              5.76                                                                              7.63                                                                              3.69                                                                              1.86                                                                              1.99 4.22                                                                              19.14                                                                             3.68 4.28                                                                              1.97                Residue 800+    3.80                                                                              .04 --  --  --  --   43.60                                                                             --  --   --  --                  Residue in Reactor                                                                            --  --  0.74                                                                              8.51                                                                              8.79                                                                              4.95 --  21.19                                                                             24.81                                                                              28.67                                                                             22.44              __________________________________________________________________________     .sup.(a) Based on 7.5 ml catalyst; helium flow rate is either 1200 ml/m o     600 ml/m                                                                      .sup.(b) Normalized on a "No Weight Loss                                      .sup.(c) Analysis (wt.%): 12.9% C.sub.1, 12.4% C.sub.2 H.sub.4, 4.0%          C.sub.2 H.sub.6, 37.7% C.sub.3 H.sub.6, 2.3% C.sub.3 H.sub.8, 28.1%           C.sub.4, 2.8% C.sub.5                                                    

                                      TABLE II                                    __________________________________________________________________________    Summary of Product Yields for Heavy Cycle Oil (Wt.%)                                        Estimat-                                                        Example(s)    ed C.sub.3.sup.-                                                                    C.sub.4 to 420.sup.- F                                                                420-800                                                                             800+                                        __________________________________________________________________________    4 As is       0     0.2     94.0  5.9                                         5 Autoclave, 575° F, 3 hr                                                            0     0.1     93.7  5.8                                         6 Thermal cracking, 950° F,                                                          0     0.1     91.5  8.3                                         0.38 sec                                                                      7 Catalytic cracking,                                                                       1.9   3.8     82.0  12.2                                        950° F, 0.38 sec.                                                      8 Catalytic cracking,                                                                       0     3.5     87.8  8.8                                         900° F, 0.75 sec.                                                      __________________________________________________________________________

                                      TABLE III                                   __________________________________________________________________________    Summary of Product Yields for Tire (backed-out data) (Wt.%)                                  Estimat-                                                       Example(s)     ed C.sub.3.sup.-                                                                    C.sub.4 to 420.sup.- F                                                                420-800                                                                             800.sup.+                                  __________________________________________________________________________     9 As is       0     0        6.1  93.9                                       10 Autoclave, 575° F, 3 hr                                                            0     0       16.8  83.6                                       11 Thermal cracking, 950° F,                                                          0     0.9     31.6  67.5                                       0.38 sec.                                                                     12 Catalytic cracking,                                                                       8.6   8.9     40.2  42.4                                       950° F, 0.38 sec.                                                      14 Catalytic cracking,                                                                       4.4   8.3     41.7  45.7                                       900° F, 0.75 sec.                                                      __________________________________________________________________________

Example 10 shows the effect of dissolution of tire in heavy cycle oil.Example 5, a control run, was made with HCO alone in the autoclave.Examples 4 and 5 show that the autoclave treatment had only a minoreffect on HCO. Comparison of the corresponding values for the tirecomponent ("as is" example and Example 10 in Table III) indicates thatsome conversion of 800° F⁺ fraction to 800° F⁻ fraction has occurred.

Thermal runs at 950° F are shown as Examples 6 and 11 in Table I.Comparisons of the "backed-out" values for the feed (See Example 5 inTables II and Example 10 in Table III) with the results of these thermalruns indicate that the total 800° F⁺ fraction of the tire is reduced by16 percent. Corresponding catalytic runs using silica-alumina catalystare shown in Examples 7 and 12. The 800° F⁺ fraction of the tirecomponent is further reduced 25 percent. However, 8.6 percent C₃ ⁻ gasis also formed. Catalytic runs at 900° F at twice the apparent contacttime resulted in conversions similar to those obtained at 950° F(compare Examples 12 and 14 in Table III).

"Backed-out" values for the tire product yields (see Examples in TableIII) are summarized by the bars on the left of each pair in FIG. 2. Thevarious "treatments" on the abcissa are arranged to show the progressiveincrease in yield of the 800° F⁻ fractions as one moves to the right ofthe axis. Since about 30 percent of the tire component is refractorycarbon black, it was of interest to subtract this amount from the"backed-out" yields. In FIG. 1 the bars to the right of each pairrepresents the so-adjusted yields.

These Examples demonstrate that, if one assumes the original tirecontains 30 percent carbon black, about 80 percent of the non-refractorypart of the 800° F⁺ fraction of the tire component is converted to 800°F⁻ material, of which about 12 percent is C₃ ⁻ gas. A comparison of thethermal and catalytic runs illustrated in FIG. 1 establishes the clearsuperiority of the process of this invention over the thermal crackingmethods employed in the prior art to treat rubber and, furthermore,supports the same inference as to treating plastics.

What is claimed is:
 1. A process for converting rubber from tires todistillates including a gasoline fraction which comprises the followingsequential steps:(a) grinding the rubber tires to a particle size withinthe range from about 1/4-inch to 1/2-inch or less; (b) separating metalsfrom ground rubber; (c) slurrying the ground rubber with a selectedpetroleum-derived stream; (d) maintaining the slurry at a temperaturewithin the range from about 500° to 700° F for a sufficient time fordissolution of the rubber to occur; (e) feeding the rubber solution to afluidized catalytic cracking zone operated at a temperature of 850° F ormore, a pressure from subatmospheric to 3 atmospheres, and in theabsence of externally added hydrogen; (f) withdrawing a cracked producthaving a liquid hydrocarbon component and a solids component; (g)separating the solids component from the liquid hydrocarbon component,and (h) distilling the liquid hydrocarbon component to recoverdistillates including a gasoline fraction.
 2. The process of claim 1wherein a portion of the distillates recovered from the liquidhydrocarbon component is the selected petroleum-derived stream.
 3. Theprocess of claim 1 wherein fibrous materials are removed from the rubbersolution in a separation means prior to feeding the rubber solution tothe fluidized catalytic cracking zone.
 4. A process for the conversionof solid rubber wastes to distillates including a gasoline fractionwhich comprises the following sequential steps:(a) grinding the wastes;(b) adding a selected petroleum-derived stream to the ground wastes; (c)maintaining the resulting mixture at a temperature of about 500° to 700°F for a sufficient time for dissolution to occur; (d) feeding theresulting solution to a catalytic cracking zone operated at atemperature of 850° F or more, a pressure from subatmospheric to 3atmospheres, and in the absence of externally added hydrogen; (e)withdrawing a cracked product from the catalytic cracking zone, and (f)distilling the cracked product to recover distillates including agasoline fraction.
 5. The process of claim 4 wherein the solid rubberwastes comprise plantation rubber, thiokols, neoprenes, nitrile rubbers,styrene rubbers, butyl rubbers, polybutadiene, silicone rubbers,acrylate rubbers, polyurethanes, and fluororubbers.